Corrugated plate, in all its forms, is extensively used in a variety of applications. For example, corrugated plate is widely used for making corrugated pipe or buildings as is disclosed in U.S. Pat. No. 3,820,295. Most recently, the use of corrugated plate having trapezoidal corrugations for the construction of high load bearing structures such as bridges, for example, has generated great interest. U.S. Pat. No. 4,120,065 discloses such a bridge construction which extensively employs trapezoidally corrugated plate as the main structural component of the bridge.
The use of trapezoidal corrugations, particularly for high load applications, is especially attractive since such corrugations have flat corrugation peaks and corrugation troughs located at a point farthest removed from the neutral axis of the corrugation. As is well known, both the section modulus and the moment of inertia of a given profile increases rapidly if the amount of material located reltively far from the neutral axis is increased. The trapezoidal cross section, as contrasted with the theretofore more common sinusoidally shaped cross sections accomplish this goal.
Inspite of the more efficient use of materials in trapezoidally corrugated plate there remains a fair amount of material in the normally slanted corrugation sides (which interconnect the corrugation peaks and troughs) in relatively close proximity to the neutral axis of the corrugation. This material, of course, adds little to the section modulus or the moment of inertia of the corrugation. At least as far as bending stresses are concerned, a good portion of the material in the corrugation sides is, therefore, simply deadweight. Such deadweight has heretofore been accepted as a necessary sacrifice for obtaining the many advantages that can be derived from a structural use of relatively inexpensive corrugated plate.